The European farm funding budget faces a 10pc cut as a result of Brexit, while defence spending may be ramped up.

The European commissioner responsible for the EU Budget said that with the UK leaving, it was a "mission impossible" to plug the funding gap without cuts.

Günther Oettinger said there were some EU countries looking for a cut to CAP payments of about 30pc. He said he believed an "acceptable" cut would be between 5pc and 10pc for both CAP and Cohesion funding, which aims to reduce economic and social disparities.

"UK leaving, to think there is no cut, nowhere, is a mission impossible," Mr Oettinger said.

"I want to speak about acceptable cuts. Means minus 5pc, up to minus 10pc, in Cohesion and CAP. But it's an open debate."

But he also suggested increases to defence spending were needed, in part because of the ongoing threat from Islamist terrorism.

"In the end, I think, we need more Europe even in defence," Mr Oettinger, the commissioner for Budget and Human Resources, told the Oireachtas Finance Committee.

"Because 'America First' can mean Europe has to give more for its own external and internal security," he added, referring to the often used slogan from US President Donald Trump.

Mr Oettinger said the annual funding gap left by the UK's departure, minus its existing EU commitments, is at least €12bn.

He said his proposal to close that gap is through an even split of cuts and additional contributions from member states.

Dangerous

Pressed by Solidarity TD Paul Murphy about defence spending in the EU, Mr Oettinger said: "I am convinced, if Europe is not investing more, it will be coming to a dangerous position.

"Seeing terrorists, seeing Islamists, and even seeing what Russia and others are investing, it's about our own security.

"I am totally convinced [of the need to increase defence spending] and I am sure Irish citizens, I can convince them as well."

Asked by Sinn Féin TD Pearse Doherty how a cut in CAP can be contemplated when there could also be an increase in EU defence spending, Mr Oettinger said: "Security is an increasing challenge, maybe."